Abstract

Question

What are the causes of syncope in patients presenting to the emergency department
(ED)?

Design

18-month cohort study.

Setting

The ED and inpatient services of a major primary and tertiary care hospital in Geneva,
Switzerland.

Patients

788 consecutive patients ≥ 18 years of age who presented to the ED with a chief
symptom of syncope. Patients with symptoms clearly compatible with seizure disorders,
vertigo, dizziness, coma, or shock were excluded. 650 patients (82%) were included
in the analysis (mean age 60 y, 52% women).

Main outcome measure

Final diagnosis.

Main results

After the initial clinical evaluation, a cause of syncope was strongly suspected in
446 patients (69%). A cause was suspected but required confirmation by selective diagnostic
testing in 67 patients (10%); the diagnosis was confirmed in 49 (73%). A specific
cause was undetermined in 155 patients (24%); 122 of these patients had an extensive
workup, and probable cause was established in 30 of these patients (25%). The final
diagnoses are summarized in the Table.

Conclusion

A standardized clinical evaluation provided a probable cause of syncope in 69% of
patients presenting to the emergency department with a chief symptom of syncope.

Commentary

Determining a cause of syncope is often difficult. Previous studies have shown that
cause could be assigned in 59% to 87% of patients (1−4).

Vasovagal syncope is common in an ED population (37% to 40%), but orthostatic hypotension
has only accounted for up to 7.6% in previous studies (1−3). These 2 diagnoses accounted
for 61% of the causes in the study by Sarasin and colleagues. The reason for the high
proportion of patients with orthostatic hypotension is not clear. Older patients have
a higher prevalence of orthostatic hypotension, a possible consequence of the physiologic
effects of aging, comorbidity, and multiple medications. Patients in previous U.S.
studies had a mean age of 41 to 44 years (1−3), whereas patients in the study by Sarasin
and colleagues had a mean age of 60 years. Thus, the older age of the patients in
this study might account for the higher prevalence of orthostatic hypotension.

Many syncope investigators expect that wider use of loop event monitoring, electrophysiologic
studies (EP), and tilt testing will lead to diagnoses in virtually all patients with
syncope. Although the authors reported a final diagnosis in 86% of patients, the high
rate was because of the result of the history and physical examination, not the result
of diagnostic tests.

The tilt-testing protocol did not use chemical stimulation. In most laboratories,
this protocol has a relatively low yield. Furthermore, EP testing was only done in
16 patients. It is possible that with chemical stimulation (isoproterenol or nitroglycerine)
during tilt testing and wider use of EP testing, many of the remaining patients could
have been assigned diagnoses.

This study confirms the central role of careful clinical assessment of patients with
syncope. The role of extensive testing with EP studies and tilt testing in the remaining
patients requires further study.